The rapid proliferation of local area network (LANs) in the corporate environment and the increased demand for time-sensitive delivery of messages and data between users has spurred development of high-speed (gigabit) Ethernet LANs. The 100BASE-TX Ethernet LANs using category-5 (CAT-5) copper wire and the 1000BASE-T Ethernet LANs capable of one gigabit per second (1 Gbps) data rates over CAT-5 data grade wire use new techniques for the transfer of high-speed data symbols.
Conventional 1000BASE-T Ethernet LAN drivers, in addition to nearly all other signal processing/communication chips and systems, use voltage reference circuits. These voltage reference circuits are able to generate relatively constant reference voltages that have a well-defined magnitude, as well as minimal process variation, temperature variation, and voltage variation.
However, conventional CMOS-based band-gap voltage reference circuits are highly prone to variations as a result of noise, power supply rejection problems, and other accuracy issues. In addition, voltage reference circuits preferably should be capable of operating at relatively low voltages with minimal current consumption, which provides yet another design challenge.
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